The lithospheric mantle varies markedly in thickness, composition, thermal structure and redox state. These differences reflect its initial formation conditions and subsequent modification by partial melting, metasomatism and tectonic reworking. The resulting chemical and physical heterogeneities can persist over geological time, recording past tectonic processes while influencing subsequent mantle melting and magma generation.
The architecture and composition of the lithospheric mantle control the generation, transport and evolution of mantle-derived magmas, as well as the mobilisation of volatiles and ore-forming elements that contribute to the metallogenic productivity of the crust. At convergent margins, a diverse range of fluids and melts released from the mantle wedge can generate significant chemical and redox heterogeneity in the overlying sub-arc lithosphere. These heterogeneities may persist through later tectonic events and influence arc magmatic activity. At divergent margins and in intraplate settings, lithospheric heating and thinning, asthenosphere–lithosphere interaction and inherited metasomatic domains can generate contrasting magma compositions and volatile fluxes. Comparisons among these tectonic settings provide an opportunity to determine how geodynamic environments, lithospheric architecture and mantle inheritance influence partial melting and the chemical/mass transfer from the mantle towards the surface.
Key questions include how: (i) the lithospheric mantle forms and evolves through geological time; (ii) compositional, metasomatic and redox heterogeneity is generated and preserved; and (iii) this inherited structure influences subsequent mantle melting, magma chemistry, volatile transfer and associated mineralisation.
This session brings together contributions from mantle petrology, mineralogy and geochemistry; experimental petrology and thermodynamic modelling; and geophysical and geodynamic studies that constrain lithospheric architecture and mantle processes. By integrating these approaches, we aim to better understand how the formation, architecture and modification of the lithospheric mantle control magmatism, volatile cycling and metallogeny through geological time.